The invention relates to an ion accelerator injection device, and belongs to the technical field of nuclear energy. The ion accelerator injection device is characterized in that the ion accelerator injection device comprises an ion beam current ECR ion source, a first solenoid, a second solenoid, an RFQ linear accelerator and a mixed type ion accelerating device, wherein the ion beam current ECR ion source is used for generating high intensity, and the first solenoid and the second solenoid are connected with the RFQ linear accelerator and the mixed type ion accelerating device through vacuum pipelines. The RFQ linear accelerator and the mixed type ion accelerating device are connected through a flange. The ion accelerator injection device has the advantages that in the accelerating process of high intensity ion beam currents, the quality of the beam currents is made to be better due to the fact that the structure is more compact; the accelerating function and the transverse and longitudinal focusing function are combined in the same high-frequency structure by using the accelerating function of a mixed type DTL, cavity shunt impedance is high, and high-frequency power dissipation is lowered greatly; acceleration is carried out by using a zero phase, acceleration efficiency is higher, the length of a cavity can be reduced effectively, and effective accelerating gradients can be improved; an additional transmission matching section is not needed between an RFQ and the mixed type DTL, manufacturing cost can be lowered, and the length of the device can be shortened. The ion accelerator injection device is mainly applied to acceleration of high intensity low energy ion beam currents, and can be applied to injection devices of high-current accelerators, industrial accelerators and other application type accelerating devices.